Chemical Mechanical Planarization (CMP) is an important process in semiconductor manufacturing. During a CMP process, a chemical reagent containing polishing liquid and a polishing pad remove material from a semiconductor wafer surface in order to planarize the wafer. The polishing liquid usually includes a solution mixed with grinding slurry particles in colloidal phase or materials in a dispersed phase. The grinding slurry particles are extremely hard, and typically have a diameter of about 10-200 nm. The polishing liquid and slurry is filtered before being used to polish a wafer in order to protect the wafer from being scratched by impurities in the slurry.
Depth filters utilize a porous filtration medium to retain particles throughout the medium, rather than on the surface of the filter medium. Depth filters are used in a variety of industrial filtration processes, such as for removing hard particles and gels from a CMP slurry. Typically, depth filters are formed from polypropylene (PP).